Vehicle overheated. It was a blown heater control valve. Right before pulling off, the engine shuddered, and the idle jumped to a very high idle. Replaced the HCV, no cooling issues.
Now it cranks up normally, and about 10 sec later revs up to a very high idle. No mechanical obstruction with the throttle.
Stalls when you try to move it. At idle very high rpm.
Any ideas.